The concentrations of NOx gases, SOx gases, and O.sub.3 gas in the air must be lowered, and to prevent the generation of such gases, various combustion devices, gas purification devices, and chemical treatment devices are employed. Nevertheless, a method of efficiently removing these harmful gases with the use of simple equipment such as an air cleaner has not been generally realized.
Nitrogen compound type gases and sulfur compound type gases in the air are accompanied by objectionable odors, which are usually eliminated by the adsorption method using activated charcoal, a masking method using perfumes, and a chemical method in which a chemical reaction among the odorous gases is carried out. These deodorants of the prior art, however, have a problem in that the deodorizing ability thereof is lost within a short time.
Senigakkaishi (Seni to Kyoto) Vol. 42, No. 12 (1986), pages 18 to 26, states that a complex compound obtained by the reaction between an Fe (II) compound and ascorbic acid in the form of a solution is able to deodorize nitrogen compound type odorous gases. Nevertheless, to the knowledge of the present inventors, such a complex compound has a weak ability for deodorizing sulfur compound type odorous gases, and although nitrogen compound type odorous gases are deodorized by adsorption by the complex compound, the amount adsorbed is limited, and therefore, a problem arises in that the deodorizing ability is lost within a short time, and further, it can not be practically applied to a gas other than ammonia. Further, such a complex compound is powderized by distillation or vacuum drying, but the preparation steps are complicated and the cost is high, because such compounds as FeSO.sub.4, FeCl.sub.2, and Fe(NO.sub.3).sub.2 are employed as the Fe (II) compound. The powdery form must be carried on, for example, zeolite, and the method of using the same is also complicated. Further, although the adsorption type or chemical reaction type purification agent of the prior art can remove a part of the gases (depending on molecular size or readiness of the reaction), it cannot remove other gases, and thus it becomes necessary to use a plurality of purification filters to separately remove the respective gases.
To purify air, there is a need to provide an air purification material which can remove harmful NOx gases, SO.sub.2 gas and O.sub.3 gas, and further can remove carboxylic group type gases, carboxylic acid type gases, nitrogen compound type gases, and sulfur compound type gases, which are accompanied by objectionable odors. Also, there is a need for the development of a purification material having a large absorption capacity when removing harmful gases contained in the exhausted gases of internal combustion engines, objectionable odors, and harmful gases generated by chemical plants, etc. In the present specification, the ability to remove all of these harmful gases and objectionable odors is hereinafter referred to as air purification power.
There is also a need to develop an air purification material which can exhibit a strong air purification power even when used over a long term.
Further, for example, an air purification material is needed which can remove harmful gases or objectionable odors without the need for complicated treatments such as distillation and vacuum drying, etc., and an air purification material which is not powdery is most preferable because it is easily handled.